Speed controlling and speed measuring centrifugal mechanism



NOV# 28, :1933.v T. ,HI BARTH 1',936,577

SPEED CONTROLLING AND SPEED MEASURING GENTRIFUGAL MEGHANISM Filed July l5., 1931 3 Sheets-Sheet l BY i Q1 i C# ATTORNEY 28, yTl BARTH 1,936,577

SPED CONTRLLING AND SPEED MEASURING CENTRIFUGAL MECHANISM Filed July 15,v 1931*. s sheetssheet 2 /0 INVENTOR.

5f- @Jafc BY ATTORNEY NOV- 28, l933 T. H. BARTH 1,936,577

SPEED CONTROLLING AND SPEED MEASURING CENTRIFUGAL MECHANISM 3 .Sheets-'Sheet 5 Filed July l5, 1931 f ATToRNEY Patented. Nov. 28, 1933 l l UNITED STATES PATENT OFFICE SPEED CONTROLLING AND SPEED MEASUR- ING CENTRIFUGAL MECHANISM Theodore H. Barth, New York, N. Y., assigner to Carl L. Norden, Inc., New York, N. Y., a corporation of New York Application July 15, 1931. l Serial No. 551,008

2 Claims. (Cl. 264-20) My invention relates broadly to speed conployed in the governor mechanism; Figs. 10 and trolling and speed measuring centrifugal mechl1 show a modified form of contact system which anism and more particularly to a compact conmay be used in the governor system of my instruction of speed controlling mechanism capavention.

5 ble of precision operation. The governor mechanism set forth herein has 60 One of the objects of my invention is to probeen found capable of controlling and measurvide a control mechanism having a high degree ing rotary speeds more closely and over a larger of precision for maintaining constant rotary mo,- range than devices heretofore known. The systOntem of my invention employs a centrifugal de- Another object of my invention is to provide vice for the precision control of rotary motors. 65 a compact construction of governing mechanism The speed controlling or measuring mechanism for rotary systems for insuring constant speed of my invention permits the use of linear scales operation without employing bulky or complior linear functioning speed setting means, and cated parts. l the controlling or speed measuring can be done Still another object of `my invention is to proover the entire speed range accurately while the 70 vide a simplied construction of centrifugal govcentrifugal elements revolve. erning mechanism wherein a control member is My invention includes a pair of pivotally conmoved in accordance with any tendency for varinected weighted arms which are rotated under ation in the speed of rotation for maintaining control of a driven shaft. A tubular member on the rotating mechanism under constant speed. the frame of the governor extends in axial align- 75 Other and further objects of my invention re ment with the driven shaft. A sleeve member side in a precision type of centrifugal govern` is longitudinally adjustable along this tubular ing mechanism as set forth more vfully in the member under control of connecting links eX- specication hereinafter following by reference tending between the weighted arms and the sleeve 5 to the accompanying drawings, in which: member. A control rod or link extends through 80 Figure 1 is an end view of the speed controlthe tubular member and connects to a Contact ling and speed measuring centrifugal mechanism arm. The contact arm is journaled under ad- Wth Darts ShOWIl partially in ONSS-Section OY `instable spring tension which tension is conillustrating the assembly of the mechanism of trollable from a control knob which carries a my nVeIltOIl; Fig- 2 iS a OP Plan View 0f the calibrated scale.- Selected tension may be placed 85 Control knOb 0f the Centrifugal governing mechupon the contact arm to counterbalance predeaniSm by Which the Operation Of the Centrifugal termined centrifugal forces. The contact sysmechanism may be regulated for a certain pretem which is made and broken by the movement determined Speed; Fig. 3 iS a diagrammatic of the contact arm is controlled at a rate devieW showing the electrical circuit arrangement pendent upon the centrifugal effort and the ten- 90 0f the COIltaCt System Operated by the governor sion obtained by the adjustment of the control mechanism of my invention for maintaining the knob. speed of an electric motor constant; Fig. 4 is The leading characteristics of the system of my a. longitudinal cross-sectional View taken along invention can be stated as follows. The only free the line 4-4 of Fig. 1 through the centrifugal and dynamically unbalanced forces of the revolv- 95 governor mechanism and the electric control ing andgactive system are the centrifugal forces system associated therewith; Fig. 5 is a lateral or couples to be measured or; that are used for cross-sectional view taken through the governor control purposes. The system may be set for mechanism on line 5-5 `of Fig. 4; Fig. 6 is a normal speed as well as for any definite control cross-sectional view through the governor housspeed or speed to be measured. The sleeve load- 100 ing on line 6--6 and showing parts of the goV- ing, counteracting and balancing the centrifugal ernor mechanism in cross-section; Fig. 7 is a forces or couples of the rotating system is done W cross-sectional view taken through the control entirely from tlie outside, and variable from zero knob which is used for adjusting the operation to the maximum-over the entire range while the of the governor mechanism of my invention; centrifugal end"`is rotating; The. weighing 0151105 Fig. 8 is an elevational view showing the adjustgoverning is done close .to a definiti@positionaofl 't able limits which are permitted for shifting the the rotating centrifugal parts in re'pect to 'their position of the control knob with respect to the axis of rotation. ff E tension mechanism of the governor system; Fig. In case a sleeve in some form is used as part 9 is a view of one of the centrifugal arms em ofthe rotating system, it rotates in or ori a'non- 110 rotating part, in order to obtain a maximum sensitivity. The external weighing or controlling devices can only be applied to centrifugal mechanism which permits the use of linear scales over the full range. The system can be used to control the speed of rotation of a conventional type of prime mover such as an electric motor. It can be used as a controlling device to limit'the speed of rotation an acting torque causes, by means of a governing brake, or it can be used to control a Variable speed gear to obtain closely a desired speed of rotation and for many other similar purposes.

The drawings illustrate the elements of my system in the simplest form, as applied to control the speed of an electric direct current motor, or servo motor. The centrifugal elements have, whether their speed of rotation is to be measured or whether they are to control to a definite speed, a fixed zero position in which they are disposed when the motor is running at its normal rate of speed. The total angular bar motion or axial sleeve motion is very small, hardly visible as such. Hence these governors can be either slightly static or astatic for this working position.

Referring now to the drawings which illustrate the elements of the system of my invention, Figs. 1-9 show a preferred form of theworking parts as applied to the control of the speed of a direct current motor. Reference character 1 indicates a shaft which is an extension of the commutator end of the electric motor, the speed of which is to be controlled. The motor frame 2 confines radial end thrust bearing 3 in which the shaft 1 is rotatably mounted and this shaft carries a fork 5 which is secured by a pin la to turn with the shaft. Bars 4 are pivoted intermediate their ends upon a pin 6 carried by the fork in crossed relation to each other. The bars 4 are identical in construction and have their center of gravity near the intersection of the axis of rotation and the tilting axis 6. Links '7, 7 can also be considered centrifugal elements, connecting cross-bars 4, 4 to sleeve 8. This sleeve rotates and slides on bushing 10, xed to housing 11 which in turn is fixed centrally to motor frame 2. Sleeve 8 also forms the outer race of a ball thrust bearing for connecting rod 9, the end of which is hardened' and forms the inner race of the thrust bearing 9a which thus is self adjusting. The connection between cross bars 4, 4 and links 7, '7 is made by means of pins 12, 12 allowing angular movement between the cross-bars and the links. The sleeve 8 is rotated by one of the links 7, the other having side clearance of its cross bar. Links 7 are pivotally connected with sleeve 8 through pins 13.

Connecting rod 9 is hinged at 14a to control lever 14 iixed to shaft 16. This shaft is mounted on ball bearings 15 in housing 11, and axially fixed by follower 17 and nut 18.

, A manually adjustable hand grip or control knob 22 is located adjacent one end of shaft 16 as shown. The knob end of shaft 16 is slotted at 16a to receive double spiral spring 19, the ends of which are fixed in spring case 2O at 20a which can be turned on a sleeve projection of housing 11, retained in place by guards 21 which also provide sufficient friction to prevent case 20 from turning. Control knob 22 is adjustably xed to spring case 20 by means of screws 23, which operate through arcuate adjusting slots 22a in knob 22 as shown in Fig. 8. A knurled edge 22h is provided on the knob 22 adjacent the cylindrical surface which carries the calibrated band member 22e. When knob 22 is turned clockwise, spring 19 is wound up exerting a turning moment on shaft 16 and lever 14 and a pulling force on connecting rod 9.

A non-conductor lever extension 24 fixed to lever 14 by `screws 14a carries contact 25 while a non-conductor extension 26 fixed to housing 11 by means of screw 26a carries an aligned contact 27. Both contacts are adjustable as shown. The micrometer screws 25a and 27a insure an accurate setting of the contacts. Further adjustment can be made by moving micrometer screw which forms a limiting stop with respect to insulated support 26.

Torque setting by turning the control knob 22 in the proper direction to tension the spring 19 tends to close contacts 25-2'7, supplying armature current to the motor of the shaft on which the governor bars are mounted. The armature and cross-bars will be accelerated until *he centrifugal couples, expressed in sleeve-force, slightly exceed the connecting rod pull due to the spring moment, when the contact is broken. Lever 14 and all parts fixed to it, including rod 9, sleeve 8 and its ball bearing, balanced crossbars 4 and links 7 for this normal position, so that gravity accelerations do not affect the speed at which the Contact is broken for a denite spring torque.

Connection is made with movable contact 25 vthrough lead 28 to terminal 28a. The lead 28 is sufficiently flexible so as not to introduce a disturbing moment in the movable system.

Referring to the wiring diagram of Fig. `3, when the armature contact is broken, friction and the work done by the motor will decelerate shaft 1 until spring 19 again closes the contacts 25-27. The motor is shown as including the armature 60 and field 61 connected with the supply circuit 62. The armature circuit is broken through contacts 25-27. Thus the motor armature receives a series of impulses, and its speed will oscillate i the contact breaking speed. For small motors, the cycles of oscillation are so rapid that these i variations are not discernible, 20 to 50 cycles occurring per second. Angular motion of the governor bars is then very small, in fact the motion at the contacts about 6/100 or 3/1000 o1' an inch, can be within the elastic deformation of the control lever. In case the motor drives parts which have much inertia or in case very low speeds are set, longer cycles result. It is clear that the external motor load must not slow the armature down below the speed set by the control knob, in other words, there can be no speed control unless the contact is active. Control knob 22 has its calibrated band member 22e marked in revolutions per minute, but it will be understood that other scale markings may be provided if So desired. A projection 28 on member 21 carries an indicator mark so that reference for the knob positions for any definite speed desired is given. The knob 22 may be oriented to shift the scale 22C in either direction with respect to the indicator 28 for orienting the calibrated scale to the desired position.

Larger motors require relay operation to handle heavy armature currents by means of a small governor to take care of arcing. The resultant motor speed does not absolutely conform lli does not apply to the use of the system for tachometers.

Figs. 10 and 11 show another form of ccntact. vHere lever 30 corresponds to lever 14 of Fig. l. Contact part. 25 takes the form of a double brush 31, whereas part 27 is in the form of a cylindrical conductor 32 as shown. Pressed against 32 but separated by a small air gap and insulating mica washer 32a there is a cylindrical guide 33. The brushes 3l just touch the part 32 when the motor is running atrits normal speed. Rotatable screw device 34, on the adjusting screw 34a4 acts as a stop to lever 30 by abutment with insulation member 64. The brushes 31 move olf and on to conductor 32 with only a. friction reaction on lever 30. oscillate or to turn, brush friction is decreased and the contact edge on brushes 31 much extended.

The control mechanism of my invention has been found highly practical in its construction and has a high degree of precision, and while I have described my invention in certain preferred embodiments I desire that it be understood that modifications may be made without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a device of the character described, a motor casing, a rotor in said casing having a shaft projecting from one end thereof, a housing extending from the said end of said casing, a yoke in said housing xed to the projecting end of said shaft, a tube extending inwardly from the outer end of said housing in alignment with the shaft and yoke and having its inner end If part 35 is arranged tov spaced from the yoke, arms disposed in crossed relation to each other and pivoted at their intersection to said yoke with their end portions diverging from opposed side portions of the yoke 'towards inner and outer ends of the housing, a

rod extending through said tube and projecting from the inner and outer ends thereof and provided with a head at its inner end,.a sleeve slidably and rotatably fitting about said tube within the housing and having a chamber at its inner end disposed beyond the inner end of the tube about the head of said rod, bearing balls in said chamber between the head and walls of the outer portion of the casing to cause the sleeve and rod to move longitudinally together and facilitate rotation of the sleeve about the tube and rod, and links pivoted to opposed portions of said sleeve intermediate ends thereof and diverging inwai-diy from the sleeve and pivoted to adjacent ends of said arms.'

2. In a device of the character described, a tubular supporting member, a sleeve concentrically disposed upon said tubular supporting member and rotatable and longitudinally adjustable thereon, said sleeve terminating i n an enlarged cylindrical chamber forming a ball race, an actuating rod axially movable through said tubular supporting member, a head on the end .of said rod disposed concentrically Within said chamber, ball bearings between said head and the ball race in said cylindrical chamber and means for imparting'sliding and rotatable movement to said sleeve and corresponding shifting said actuating rod in an axial direction.

THEODORE H. BARTH. 

